A probe card having an array of probe needles extending therefrom is typically used to test dies on a wafer of semiconductor devices to identify faulty dies. Such testing is often done before cutting the dies from the wafer and before packaging the dies into finished semiconductor components. The probe card provides temporary electrical contact between the die and a tester. The electrical contact with the die is made with probe tips of the probe needles.
FIG. 1 is simplified schematic showing a typical flipped-head probe testing machine 30 with a probe card 32 therein. A ring insert 34 is used to hold the probe card 32 in place in a head plate 36. A test head 38, which contains the tester circuitry (not shown), is electrically coupled to the top side of the probe card 32 via an array of pogo-pins 40. In the flipped-head probe testing machine 30 shown in FIG. 1, the probe card 32 and test head 38 remain fixed during use, and a wafer 42 is positioned relative to the probe card 32 on a movable wafer chuck 44. The wafer chuck 44 moves within the flipped-head probe testing machine 30, wherein wafers can be loaded and moved into position for testing. Manually adjustable head plate support columns 46 hold the head plate 36 and probe card 32 in place. During setup of the flipped-head probe testing machine 30, the head plate 36 is adjusted parallel with the wafer chuck 44 by manually adjusting the height of the head support columns 46.
The array of probe tips 48 of the probe needles 50 are typically arranged in a pattern matching the layout of the bond pads or bumped pads (e.g., for a ball-grid array) of a particular die design. For example, the array of probe needles 50 may be arranged in a square pattern for a single large die that is 1.1 inches diagonally across the square. In another application, the array of probe needles 50 may be arrange in three square patterns with a diagonal distance of 1.2 inches across the three squares for testing three dies at once, for example. Hence, a probe card 32 may have hundreds or even thousands of probe needles 50. As the technology of semiconductor devices progress, the number bond pads or bumped pads typically increases and the size of the individual pads typically decreases, while the cost of such semiconductor devices are expected to decrease. Thus, the demands on the precision of probe cards and the complexity of probe cards have escalated. Hence, a need exists for more precisely aligning a probe card with a die.
The increase in complexity of probe cards has led to increases in the cost of probe cards. For example, a typical probe card in the past may have cost only about $500-$2500. In contrast, today a probe card may cost as much as $60,000. The cost of probe cards can lead to costs in the millions per month for semiconductor manufacturers. Hence, there is an increased need for increasing the life of probe cards.